The current rate of new construction, whether it be commercial buildings or residential dwellings, presents unique problems to the construction industry. Certainly, one of these problems is the provision of ready accessibility of utilities such as electricity, gas, and telephone. Often overlooked, however, and maybe more important, is the need to provide adequate and effective sewage treatment and ultimate disposal. While it is often taken for granted that no problem will be presented in providing waste treatment systems, more experienced and sophisticated construction planners recognize the essentiality of adequately integrating various considerations bearing upon such a system into their planning at a very early stage.
Typically, in urban areas, sewer systems are provided, and property owners need not individually plan for the provision of a waste treatment system. Various factors have, however, come to dictate that onsite systems be employed. These factors include, for example, the inadequacy of common sewer systems, the high cost of sewer system construction, and various political considerations. The trend is, therefore, toward such onsite systems.
Systems of this type incorporate a large receptacle into which raw sewage passes after it leaves a building which it is designed to service. This tank is constructed, typically, having a baffle arrangement to retain and store the bulk of the solids from the sewage. The capacity of the tank is, of course, limited, and, at various times in its life, it must be pumped, the solid waste being transported by, for example, a tank truck to a disposal site at some distance from the location of the residence or other building which is serviced by the particular tank.
The liquid sewage, or effluent, from the tank, after the bulk of the solids are removed therefrom, is, typically, channeled to a distribution box. Although a very high percentage of the solids are removed by the baffles in the tank and stored therein, a small amount of suspended solids remain entrained in the effluent. Typically, suspended solids in a volume of between 130 and 160 parts-per-million remain in the effluent after it leaves the sewage tank.
The distribution box, in turn, directs the effluent into a soil treatment system such as a drainfield for treatment of the effluent. Drainfield construction typically includes a perforated pipe extending laterally from the distribution box. The pipe is, in turn, surrounded by crushed rock. The rock is covered with a soil barrier, and back filling with soil to grade is effected to complete a drainfield trench.
A trench so constructed is commonly of a width of between 24 and 30 inches and to a depth of between 2 and 3 feet. The dimensional parameters of the trench will, of course, vary depending upon anticipated sewage effluent volume and the conditions of the soil in which the trench is constructed.
Effluent directed out of the distribution box passes, first, through the perforated pipe. It disperses outwardly through the perforations and into the rock surrounding the pipe. Thereafter, it settles into the soil where it is treated naturally by decomposition. Decomposition can be either an aerobic or anaerobic process. In either case, however, the biological process effects digestion of the small organic materials, bacteria, fecal matter, and nutrients in the effluent.
In older systems, onsite treatment systems employed a single drainfield trench. A problem which resulted was at least temporary saturation of a portion, if not all, of the trench. While such saturation might have been only occasional, the consequences were serious, if not catastrophic. When the soil treatment system trench became so saturated that it could no longer absorb effluent coming out of the distribution box, the effluent would back up through the distribution box and sewage tank into the home or other building which the system serviced. This consequence tends to be messy, costly, and generally frustrating to the owner of the building. As a result, many property owners would avoid finishing areas in their homes below grade because of the possibility of back-up occurring.
One solution which technology has proposed is the provision of multiple soil treatment system segments or trenches. When one segment becomes super-saturated, a valve can be manipulated to redirect the effluent to another segment. While the effluent is redirected to the alternative segment, the first segment from which the effluent has been diverted can be effecting decomposition and can be drying.
For various reasons, therefore, "resting" of a soil treatment system segment is advantageous. Not only does "resting" work to minimize the likelihood of backing-up, but it is believed that it also functions to improve the soil structure of the various fields.
For these reasons, various political subdivisions throughout the United States and other countries have mandated that two alternate trenches be provided in all onsite sewage treatment systems. In fact, in San Mateo County, CA alternation of trenches has been a county requirement since 1969.
Problems yet remain in state-of-the-art structures. For example, typically, onsite systems, even where alternative trenches are employed, utilize only two field segments. Where large volumes of effluent are processed, two segments may be insufficient to preclude backing-up.
Even if a sufficient number of field segments is provided, however, alternation among two or more is "scheduled" at regular time intervals rather than being implemented in response to conditions. As will be able to be seen, therefore, if particularly heavy usage occurs during any one of the "scheduled" periods, backing-up might still occur.
Another problem is one wherein, even if the owner of the building being serviced by a treatment system were able to know when conditions dictate rotation from one segment to another, there is an initial period when back-up could occur even before the operative field segment could be changed. No fail-safe systems are, to applicant's knowledge, available which effect diversion of the effluent away from the conduit interconnecting the sewage tank and distribution box.
A number of other problems exist in such systems. While it is not desirable to permit large solids to pass into the perforated pipes of the treatment systems exiting from the distribution box, since the perforations could become occluded by such solids, the passage of some small solids suspended in the effluent into the soil treatment system trenches further decomposes in the soil treatment system.
Additionally, distribution boxes need to be durable in view of the corrosive and pressure environments to which they are exposed. Because of the depths to which they are planted, significant pressures can be exerted thereon.
It is to these problems in the prior art and desirable features dictated in view of those problems that the present invention is directed. It is an improved apparatus for filtering and valving the effluent from a sewage tank to one or more soil treatment system segments.